Questão de Inglês com gabarito

  The following are examples of types of air traffic
controllers:
  Tower controllers direct the movement of vehicles on
runways and taxiways. They check flight plans, give pilots
[5] clearance for takeoff or landing, and direct the movement of
aircraft and other traffic on the runways and other parts of the
airport. Most work from control towers, as they generally
must be able to see the traffic they control.
  Approach and departure controllers ensure that aircraft
[10] traveling within an airport's airspace maintain minimum
separation for safety. They give clearances to enter controlled
airspace and hand off control of aircraft to en route
controllers. They use radar equipment to monitor flight paths
and work in buildings known as Terminal Radar Approach
[15] Control Centers (TRACON). They also provide information
to pilots, such as weather conditions and other critical
notices.
  En route controllers monitor aircraft once they leave an
airport's airspace. They work at air route traffic control
[20] centers located throughout the country, which typically are
not located at airports.
  Each center is assigned an airspace based on the
geography and altitude of the area in which it is located. As
an airplane approaches and flies through a center's airspace,
[25] en route controllers guide the airplane along its route. They
may adjust the flight path of aircraft for safety and collision
avoidance.

Consider this excerpt from the text:

“They work at air route traffic control centers located throughout the country, which typically are not located at airports.” (lines 19, 20 and 21) 

All the following sentences about the underlined word are correct, except: